section{
    width:100%;
    position: relative;
    background: black;
    padding:0 20px;
    margin-top:60px;
    box-sizing:border-box;
}

section.main{
    padding: 0;
    margin-top:0px;
}
section div.main_background{
    background: 
    url(../images/lense.jpg);
    background-size:cover;
    background-position:50% 50%;
    width:100%;
    padding-top:70.3125%;
    position: relative;
    overflow: hidden;
    /*margin-bottom:20px;*/
}

section div.main_background:nth-child(2){
    background: url(../images/speakers.jpg);
}

section div.main_background:nth-child(3){
    background: url(../images/projector.jpg);
}

section div.main_background:nth-child(4){
    background: url(../images/camera.jpg);
}

section div.main_background:nth-child(5){
    background: url(../images/theatre.jpg);
}

section div.main_background:last-child{
     margin:0;
}

section div.main_background_pos{
    background: 
    url(../images/lens-flare.png);
    background-size:cover;
    background-position:50% 50%;
    width:100%;
    padding-top:81.4%;
    position: absolute;
    left:0;
    top:0;
}

section .main_background_info{
    position: absolute;
    top:50%;
    left:50%;
    transform:translate(-50%,-50%);
    width:100%;
    text-align: center;
}

section  .main_background_info p{
    color:#fff;
    font-size: 104px;
    font-weight: 200;
    font-family: 微软雅黑, 微软雅黑;
    text-align: center;
}

section  .main_background_info span:first-child{
    display: inline-block;
    width:90px;
    height: 15px;
}

section  .main_background_info span:first-child img{
    width:100%;
    vertical-align:top;
}

section  .main_background_info span:nth-child(2){
    color:#fff;
    display: inline-block;
    font-size: 22px;
}

section .main_info{
    display: block;
    color:#fff;
    max-width:600px;
    width:90%;
    margin: 0 auto 50px auto;
}

section .main_tech{
    text-align: center;
}

section .main_tech a{
    display: inline-block;

}

section .main_tech a img{
    vertical-align: top;
}

section .main_title{
    text-align: center;
    margin:50px 0;
}

section .main_title span:nth-child(1){
    display: inline-block;
    width:90px;
    height: 15px;
}

section .main_title span:nth-child(1) img{
    width:100%;
    vertical-align:top;
}

section .main_title span:nth-child(2){
    color:#fff;
    display: inline-block;
    font-size: 22px;
}

section .main_info_bottom{
    text-align:center;
    color:#fff;
}

section .main_info_bottom p:nth-child(1){
    font-size: 55px;
    margin-bottom: 20px;
}

section .main_info_bottom p:nth-child(3){
    padding-bottom:100px;
}

section.main>ul{
    overflow: hidden;
}

section.main>ul li{
    float: left;
    width:25%;
    position: relative;

}


section.main>ul li a{
    text-decoration: none;
    
}
section.main>ul li .main_more{
    display: inline-block;
    padding:10px 20px;
    background: #6dc3f4;
    color:#000;
    margin-top:10px;
    position: relative;
    overflow: hidden;
    z-index: 3;
}

/*

 width,height 100%是包括padding的 
 main_more_hide层级必须最低 
 main_more层级最低
 父级.main>ul li>div中间层级

*/
.main_more .main_more_hide{
    /*display: block;*/
    width:100%;
    height: 100%;
    position:absolute;
    background:#fff;
    top:100%;
    left:0;
    z-index: -1;
}

section.main>ul li img{
    width: 100%;
    vertical-align: middle;
}

section.main>ul li h3{
    color:#6dc3f4;
}

section.main>ul li>div{
    position: absolute;
    bottom:30px;
    left:30px;
}

section.main>ul li>div h1>a{
    color:#fff;
    font-size: 28px;
}

section.main .main_bottom{
    width: 100%;
    height: 50px;
    position: relative;
    background: #fff;
}

section.main .main_bottom button{
    padding: 10px 20px;
    color:#fff;
    background: #393d43;
    margin:0 auto;
    text-decoration: none;
    position: absolute;
    left:50%;
    bottom:0;
    transform:translateX(-50%);
    -webkit-transform:translateX(-50%);
    -moz-transform:translateX(-50%);
    -ms-transform:translateX(-50%);
    border:none;
    cursor: pointer;
    outline: none;
    font-size: 18px;
}


nav ul:last-child li:first-child{
    background:#000912;
}   

nav ul:last-child li:first-child a{
    color:#fff;
}

@media (max-width: 1366px){
    section.main>ul li{
        width:33.33%;
    }

}


@media (max-width: 768px){
    section{
    margin-top:102px;
    }

    section  .main_background_info p{
        font-size:35px; 
    }
    section  .main_background_info span:first-child img{
        vertical-align: bottom;
    }
    section  .main_background_info span:nth-child(2){
        font-size: 16px;
    }
    section.main>ul li{
        width:50%;
    }

    section.main .main_bottom button{
        display: block;
        width: 100%;
    }

    .swiper-container{
        margin:0px;
    }

}

@media (max-width: 540px){
    section.main>ul li{
        width:100%;
    }

    section .main_info_bottom p:nth-child(1){
    font-size: 30px;
    margin-bottom: 20px;
    }

}

@media (max-width: 480px){
    section  .main_background_info p{
        font-size:30px; 
    }
    section  .main_background_info span:first-child img{
        vertical-align: bottom;
    }
    section  .main_background_info span:nth-child(2){
        font-size: 12px;
    }
    section .main_info_bottom p{
        font-size: 14px;
    }
    section .main_info_bottom p:nth-child(1){
    font-size: 26px;
    margin-bottom: 20px;
    }
}
